检索结果-南通市图书馆

碳价格如何影响企业绿色投资与信用风险--基于预期收益与违约成本的权衡分析

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

中国工业经济 2024年第8期 118-136页

作者：牛华伟曹玲玲不详

“双碳”目标下企业的绿色投资及风险管理策略受预期碳价格变动的影响,且绿色投资最优规模需要企业权衡投资不足的机会成本和绿色债务无法偿还的违约成本。考虑外部融资风险和随机流动性冲击,本文建立一个理论模型,量化研究碳价格对企... 详细信息

“双碳”目标下企业的绿色投资及风险管理策略受预期碳价格变动的影响,且绿色投资最优规模需要企业权衡投资不足的机会成本和绿色债务无法偿还的违约成本。考虑外部融资风险和随机流动性冲击,本文建立一个理论模型,量化研究碳价格对企业绿色投资规模和绿色债券信用利差的影响及其机制。碳资产可被质押使得碳价格在直接影响违约边界的同时,通过影响绿色投资规模间接影响企业的违约边界,且由于碳价格对违约概率和违约成本的非对称影响,碳价格对信用风险的直接影响大于间接影响。理论与实证结果表明:碳价格的提高能降低绿色投资企业的信用风险,降低绿色债券信用利差;存在碳价格的高、低双重门槛决定企业的最优绿色投资决策,当碳价格低于影子价格时,随着碳价格提高,最优绿色投资规模增加,而当碳价格处于显著大于影子价格的较高水平时,碳价格的提高反而降低最优绿色投资规模。此外,当碳价格大于(小于)高(低)门槛值时,企业绿色债券信用利差随着绿色投资规模的增加而增加(减少)。本文有助于深入理解碳定价机制对企业绿色投资决策和绿色债券定价的作用机理,为进一步完善碳市场建设与绿色投融资政策提供了重要启示。

关键词：绿色投资碳价格信用利差影子价格绿色债券

2000-2020年青海湖流域植被净初级生产力时空格局及驱动分析

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

水土保持研究 2024年第5期31卷 327-336,343页

作者：李文斌曹生奎曹广超赵浩然陈链璇侯瑶芳青海师范大学地理科学学院西宁810008 青海省自然地理与环境过程重点实验室西宁810008 青海师范大学青海省人民政府—北京师范大学高原科学与可持续发展研究院西宁810008

[目的]明确2000—2020年青海湖流域植被净初级生产力(Net primary productivity,Npp)时空格局变化特征,探究影响植被Npp的主要因素及驱动比例,为青海湖流域基础科学研究提供参考。[方法]以青海湖流域为研究区域,基于2000—2020年植被Np... 详细信息

[目的]明确2000—2020年青海湖流域植被净初级生产力(Net primary productivity,Npp)时空格局变化特征,探究影响植被Npp的主要因素及驱动比例,为青海湖流域基础科学研究提供参考。[方法]以青海湖流域为研究区域,基于2000—2020年植被Npp、气温、降水量、植被覆盖度、人类活动强度数据,采用ArcGIS空间分析、地理探测器模型等方法,分析植被Npp在子流域、海拔、微地形上的时空变化,并对流域Npp与气温、降水量和植被覆盖度的相关性及植被Npp的驱动要素进行研究。[结果](1) 21年间青海湖流域年植被Npp逐年波动上升,增速为2.22 g C·m^(2)/a,空间上自西北向东南递增。(2)年植被Npp与年均气温、年降水量、年植被覆盖度的显著相关区域占流域面积比依次为40%,9%,59%。年均气温和年降水量与年植被Npp的一级偏相关系数显著区域占流域面积比分别是59.26%和33.39%。(3)驱动分析表明气温(q=0.58)、海拔(q=0.54)、人类活动(q=0.38)是流域Npp的主要驱动因子,并且因子交互解释力强于单因子解释力。[结论]2000—2020年青海湖流域植被Npp整体逐年增长,在海拔、子流域和微地形格局上表现出显著的空间分异性,气温、海拔、人类活动的交互驱动是流域Npp的主要驱动类型。

关键词：青海湖流域植被净初级生产力时空格局地理探测器

维普期刊数据库博看期刊

The Effect of Titania-coating on Electrochemical Characteristics of CMS in pC-Based Electrolyte

在线全文

学校读者我要写书评

暂无评论

复旦学报（自然科学版） 2005年第5期44卷 857-858页

作者： J. cao L.C. Yang T. Zhang Y.p. Wu H.q. Wu Deparment of Chemistry ＆ Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China

Lithium-ion batteries have been widely used in portable electronic devices due to their high voltage and high energy density. Most research has concentrated on improving their performance such as capacity, cycling characteristics and low temperature range. propylene carbonate (pC)-based electrolytes are more desirable than ethylene carbonate (EC)-based electrolytes because of their low-temperature characteristics[1]. Unfortunately, pC is not used in commercial lithium-ion batteries because solvent decomposition and graphite exfoliation occur when lithium intercalates[2].

关键词：锂离子电池二氧化钛丙烯碳酸盐溶胶凝胶体电化学

Effect of Silver Content on Microstructure and properties of Brass/steel Induction Brazing Joint Using Ag-Cu-Zn-Sn Filler Metal

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2011年第4期27卷 377-381页

作者： J. cao L.X. Zhang H.q. Wang L.Z. Wu J.C. Feng State KeyLab of AdvanCed Welding production Technology Harbin Instituteof Technology Harbin 150001 China Center for Composite Materials and Structures Harbin Institute of Technology Harbin 150001 China

The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 Mpa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.

关键词： Induction brazing Brass Steel Microstructure Tensile strength

EIS ANALYSIS ON THE ANODIC pROCESS OF ZINC IN AN ALKALINE SOLUTION

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 912-922页

作者： Y.Zheng J.M.Wang H.Chen J.q.Zhang C.N.cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／ChineseStateKeyLaboratoryforCorrosionandProtectionInstituteofMetalReseachTheChineseAcademyofSciencesShenyang110016China

yThe　EIS　on　theanodic　process　of　pure　Zn　in　an　alkaline　solution　wereperformed　and　fitted　using　the　expression　of　Faradic　admittance,based　on　which　the　mechanism　of　the　process　was　***　results　showed　that　besides　electrode　potential　E　the　electrochemical　reaction　rate　was　affected　by　the　adsorption　of　Zn(OH)ads　on　the　electrode　surface　and　the　diffusion　of　in　the　electrolyte　in　active　region,and　only　by　the　covering　of　passivation　layer　on　the　electrode　surface　in　both　transitive　and　passivation　***　equivalent　circuit　sapplied　in　these　various　circumstances　were　proposed　and　the　variation　of　some　parameters　and　state　variables　was　also　discussed.

关键词： Zn alkalinesolution anodicprocess EIS

ELECTROCHEMICAL NOISE FEATURES OF pURE ALUMINUM DURING pITTING CORROSION IN NEUTRAL NaCl SOLUTION

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 20-30页

作者： F.H.cao Z.Zhang Y.L.Cheng J.F.Li J.q.Zhang J.M.Wang C.N.cao Department of Chemistry Zhejiang UniversityHangzhou 310027China State Key Laboratory for Corrosion and protection of Metals Institute of Metal ResearchThe Chinese Academy of SciencesShenyang 110016China

Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated, and the breakdown and restoration of passive metal's film are studied using potentiodynamic scanning (pDS) measurements and electrochemical impedance spectroscopy (EIS) technique. Two capacitance loops are observed in the Nyquist plots in two kinds of concentration, and the corrosion process is under activation control at first, then become diffusion control within the oxide film and corrosion products of (Al(OH)p-mCl-m) accumulated on the surface of the corroding electrode. It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit. The corrosion rate deterministic step does not involve Cl-.

关键词： pure aluminum pitting corrosion electrochemical noise electrochemical impedance spectroscopy potentiodynamic scanning

两样本孟德尔随机化方法对甲状腺功能减退症与肠道菌群因果关系研究

在线全文

学校读者我要写书评

暂无评论

中国病原生物学杂志 2024年第10期19卷 1167-1171页

作者：徐剑春张秀琴曹煜贵州医科大学大健康研究院贵州贵阳550025 贵阳市第六医院

目的通过孟德尔随机化研究(Mendelian randomization, MR)分析肠道菌群和甲状腺功能减退症之间的因果关系。方法从MiBioGen数据库下载人类肠道菌群数据集,保留196个已知菌群(9个门、16个纲、20个目、32个科和119个属)用作暴露因素,工... 详细信息

目的通过孟德尔随机化研究(Mendelian randomization, MR)分析肠道菌群和甲状腺功能减退症之间的因果关系。方法从MiBioGen数据库下载人类肠道菌群数据集,保留196个已知菌群(9个门、16个纲、20个目、32个科和119个属)用作暴露因素,工具变量为与暴露因素强相关且相互独立的单核苷酸多态性(single nucleotide polymorphism, SNp)。从全基因组关联研究数据库下载包含30 155例患者和379 986例对照的甲状腺功能减退症数据集用作结局变量。分别采用逆方差加权(IVW)法、加权中位数(WM)法、MR-Egger检验进行两样本MR分析,以优势比(odds ratio, OR)评估肠道菌群与甲状腺功能减退症的因果关联;利用留一法进行敏感性分析,采用MR-Egger截距测试和MR-pRESSO全局检验来检测水平多效性,Cochran q检测异质性。结果共发现196个肠道微生物群类中有6菌类与甲状腺功能减退症发病风险有因果关联(pp152个。IVW分析结果显示慢球菌纲[OR=1.003,95%置信区间(confidence interval, CI)(1.001,1.005),pp=0.005]、斯莱克菌属[OR=1.002,95%CI(1.000,1.005),p=0.0048]和脱硫弧菌目[OR=1.003,95%CI(1.002,1.006),p=0.0349]、放线菌门[OR=1.004,95%CI(1.002,1.006),p=0.0385]、与甲状腺功能减退症呈正相关;消化球菌科[OR=0.995,95%CI(0.992,0.998),p=0.0031]与甲状腺功能减退症呈负相关。此外,留一法敏感性分析结果稳定,MR-Egger截距测试和MR-pRESSO全局检验无水平多效性,Cochran q检验不存在异质性。结论肠道菌群和甲状腺功能减退症之间存在因果关系,慢球菌纲、放线菌门、巴氏杆菌科、斯莱克菌属和脱硫弧菌目可增加甲状腺功能减退症发病风险,消化球菌科可降低甲状腺功能减退症发病风险。

关键词：甲状腺功能减退症肠道菌群孟德尔随机化研究因果关系

基于Sentinel-5p的长三角大气NO_(2)污染特征及影响因子分析

在线全文

学校读者我要写书评

暂无评论

安全与环境学报 2024年第2期24卷 767-777页

作者：曹念文宋坤杰方文圣南京信息工程大学气象灾害预报预警与评估协同创新中心南京210044

基于哨兵-5p(Sentinel-5 precursor,Sentinel-5p)卫星反演的NO_(2)柱浓度数据,利用Google Earth Engine云平台,结合自然因子和人为社会因子数据,分析长三角地区大气NO_(2)柱浓度的污染特征及影响因素。结果显示:(1)Sentinel-5p卫星反演... 详细信息

基于哨兵-5p(Sentinel-5 precursor,Sentinel-5p)卫星反演的NO_(2)柱浓度数据,利用Google Earth Engine云平台,结合自然因子和人为社会因子数据,分析长三角地区大气NO_(2)柱浓度的污染特征及影响因素。结果显示:(1)Sentinel-5p卫星反演的NO_(2)柱浓度数据与地面观测站NO_(2)质量浓度具有较好的相关性(r≥0.59,pq均在0.6以上。

关键词：环境学 NO_(2)污染长江三角洲 Google Earth Engine 地理探测器

ELECTROCHEMICAL STUDY ON THE LOCALIZED CORROSION OF TWO DIFFERENT TEMpER LY12 ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 609-619页

作者： F.H. cao L. Guo L.J. Zhang Z. Zhang J. q. Zhang Department of Chemistry Yuquan Campus Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and protection of Metals Institute of Metal Research The Chinese Academy of Sciences Shenyang 110016 China

The corrosion behavior of two different aged LY12 alloys in EXCO （234g/L NaCl, 50g/L KNO3 0.1M HNO3） and MIL-H-600 （35g/L NaCl, 5g/L （NH4）2SO4） solutions were studied using electrochemical impedance spectroscopy （EIS） in conjunction with SEM technique respectively, and the pH variation of the above accelerated corrosion solution during materials corroding was also measured to characterize the corrosion processes. At the beginning of corrosion, EIS plots exhibited two capacitive arcs in the high frequency range （Cd） and mediate frequency range （ Cf） originating from the original corroded surface and the newly formed interface respectively, and a low frequency inductive loop due to the relaxation phenomenon of reaction intermediates. In the EXCO,solution, the EIS results showed that once the exfoliation corrosion occurred, the inductive loop disappeared. The results also showed that the exfoliation corrosion susceptibility of state T6 is much higher than that of state T3, but the intergranular corrosion susceptibility has a reverse order. Based on the relationship of EIS results with SEM and metalloscopy morphologies of the corroding substrates and physic-chemical meaning of EIS parameters, an index （Cf/Cd） has been proposed to characterize the extent of the localized corrosion, which variation tallies with the real corrosion extent correctly. Meanwhile, good agreement was found between the experimental results and the electrochemical model proposed and, good coherence between the electrochemical features and the distribution type of constituent particles of corroding material was observed.

关键词： electrochemical impedance spectroscope LY12 alloy exfoliation corrosion intergranular corrosion